1. Field of the Invention
The present invention relates generally to optical fiber devices and methods, and in particular to improved systems and methods for reducing group delay ripple in a dispersion compensating fiber Bragg grating.
2. Description of Prior Art
A fiber Bragg grating (FBG) is an optical device having a central waveguide for carrying optical data signals of varying wavelengths. An FBG includes a number of grating regions, each of which causes signals of a particular wavelength, known as the “Bragg wavelength,” to be reflected back down the length of the grating, while allowing other wavelengths to pass. An FBG may be designed for use as a dispersion compensator that introduces into an optical link a wavelength-dependent group delay having a slope opposite to that of a wavelength-dependent group delay in an optical link. The FBG group delay is created by designing the grating regions such that the distance traveled along the length of the grating by a signal varies in a generally linear relationship with the signal's wavelength.
However, for a number of reasons including, for example, manufacturing imperfections, the group delay exhibited by a dispersion compensating grating (DCG) typically includes an undesirable “ripple” that may lead to transmission slowdown and errors, particularly where an optical transmission system includes a plurality of FBGs. There thus exists a need for systems and techniques for reducing this group delay ripple to an acceptably low level.